This tiny script check whenever a game is installed on Windows and where it is.
It doesn't check if the files are still in the indicated folder.
The function checkGames (that you can add to your code without problems, this repo is under The Unlicense) returns an array like this [int gameId, bool isInstalled, string gameName, string installLocation].
You can use it this way:
from checkGames import *
portal2 = checkGames(620)
if portal2[2]:
print(portal2[2], "is installed at", portal2[3])
else:
print(portal2[0], "is not installed")